This application is based upon and claims benefit of priority of Japanese Patent Application No. 2001-326413 filed on Oct. 24, 2001, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a system for installing a control program in an electronic control unit mounted on an automotive vehicle. The control program is installed at an end of a manufacturing line after the electronic control unit has been mounted on the vehicle. This system is often referred to as an end-of-line (EOL) program-installing system.
2. Description of Related Art
Recently, an electronic control unit (referred to as ECU) which is common to various types of automobile vehicles is used for reducing a manufacturing cost of the ECU. The common ECU is mounted on the various types of vehicles in a manufacturing line, and a control program specific to a vehicle type is installed in the ECU mounted on that type of vehicle at an end of a manufacturing line.
An example of the EOL program-installing system is disclosed in JP-A-4-246730. In a memory included in an ECU which is common to various types of vehicles, a code for identifying a type of vehicle on which the ECU is to be mounted and control programs covering all the types of vehicles are pre-installed in the ECU. At an end of a manufacturing line after the ECU is mounted on the vehicle, a program for selecting a control program, which is specific to the vehicle on which the ECU is mounted, from among the pre-installed control programs is installed in another memory contained in the ECU. Such an EOL program-installation is performed according to the vehicle type identifying code pre-installed in that ECU.
A memory capacity of the ECU, however, becomes unnecessarily large, because various control programs corresponding to all the vehicle types have to be stored in the memory. This makes the ECU expensive. Taking a program for controlling an air-conditioner as an example, control programs corresponding to various kinds of air-conditioners have to be pre-installed in the ECU, because it is unknown which kind of air-conditioners is used in a particular vehicle on which the ECU is mounted. Only one program actually used is selected from among many pre-installed programs, and other non-selected programs are useless. Since a large memory capacity is required in the ECU due to sophisticated electronic controls in recent automobiles, the problem of the memory capacity is becoming more serious.
On the other hand, it is conceivable to provide a blank memory region for each control function in the ECU without pre-installing programs and to install programs for each function suitable to a particular vehicle type. In this case, however, the blank memory capacity has to cover a largest capacity necessary for a particular vehicle, even though such a large capacity is unnecessary for most vehicles. For example, taking a control function for controlling air-conditioner, a large memory region for the air-conditioner control may be required in a particular vehicle type while only a small memory region is necessary for other vehicle types.
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an EOL program-installing system in which a memory capacity of an ECU can be saved.
Various types of automotive vehicles are manufactured in a same manufacturing line, and an electronic control unit which is common to all vehicle types is mounted on each vehicle. In the end of line (EOL) program-installing system, a control program specific to each vehicle type is installed in the ECU at the end of the manufacturing line. The EOL program-installing system is composed of a program-installing device and each ECU mounted on the vehicle. After the ECU is mounted on the vehicle, the ECU and the program-installing device is connected through a communication cable.
The ECU mounted on the vehicle receives a signal identifying the vehicle type from the vehicle. The identifying signal may be an electric signal having a frequency specific to each vehicle type or a voltage signal having a voltage level specific to each vehicle type. Data for identifying the vehicle type is formed in the ECU based on the signal fed from the vehicle to the ECU and is sent to the program-installing device.
The program-installing device includes an object library that stores plural program modules (referred to as objects) for each control function. An object corresponding to the identified vehicle type is selected from among plural objects stored in the object library for each control function. Objects thus selected for each control function are linked together to formulate a control program to be installed in the ECU mounted on the vehicle, the type of which is identified. The formulated control program specific to that vehicle is installed in the ECU mounted on that vehicle through the communication cable connecting the program-installing device to the ECU.
Since only the control program necessary to the identified vehicle type is mounted on the ECU, a memory capacity in the ECU is considerably saved. Further, a memory capacity in the program-installing device is also saved since the control programs covering all vehicle types are formulated by selecting necessary program modules from the object library.
The program-installing system may include a function for inspecting whether the control program formulated in the program-installing device is correctly installed in the ECU. For this purpose, a checking value representing the control program actually installed in the ECU is calculated and is compared with a checking value representing the control program formulated in the program-installing device. A Check-Sum or a Cyclic-Redundancy-Check value may be used as the checking value. Further, the vehicle type identified according to the identifying data sent from one ECU may be confirmed by comparing the identifying data with other identifying data sent from other ECUs mounted on the same vehicle. Correctness of the program installation is guaranteed by the inspection and confirmation functions in the system.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings.